The 701-room Riu Guanacaste is a lot like a Riu anywhere, with a good beach, a huge, raucous pool, an energetic entertainment staff, and a party-hearty, booze-fueled atmosphere. Rooms are nothing special, and a la carte restaurant reservations need to be made a day in advance. If you're after a convenient, typical all-inclusive experience, this is it; if you're looking to experience local charm, not so much.
Guanacaste is a dry, sparsely populated area of the country that's known for its beautiful beaches (including ones where sea turtles nest), surfing, snorkeling, deep sea fishing, and its string of large resorts. The region is home to seven national parks, including Rincon de la Vieja Volcano National Park, where visitors can hike past boiling mud pots and smoking fissures. Guanacaste has a lower elevation than other areas of the country and an arid climate, so there are no rain forests here, but the dry tropical forests are still wildlife rich: Visitors can spot howler monkeys, sloths, white-faced capuchin monkeys, and iguanas.